Keeping Mavic battery at 50-60%

[Rocky43]

How often should i charge it up and fly it ?

 

[4wd]

It will gradually drop but if you can't use it you can check the level with a quick press perhaps once a month or so.
You would probably be OK for as much as six months but total lifespan might suffer, I'd suggest try to charge up and either somehow use it or let it self discharge about once a month if you are at home.

For most users, provided you don't put it away discharged below 50% there's no need to worry, much nowadays.
The drone will likely become obsolete or replaced within the normal life of a battery.
I suspect the typical regular use period of most drones is around two years before owner gets bored or buys a newer model - which will invariably have slightly different deign so you have to buy extra batteries again.